2. 1 Chp 1: Welcome to the World of Chemistry & Chp 5: Measurement and calculation

3. 2 Goals: 1.To understand the importance of learning chemistry 2.To define chemistry 3.To understand and illustrate scientific thinking 4.To describe the method scientists use to study nature 5.To develop successful strategies for learning chemistry 6.To show how very large or very small numbers can be expressed in scientific notation 7.To learn the English, metric, and SI systems of measurement 8.To use the metric system to measure length, volume and mass 9.To learn how uncertainty in a measurement arises 10.To learn to indicate a measurement’s uncertainty by using significant figures 11.To learn to determine the number of significant figures in a calculated result 12.To learn how dimensional analysis can be used to solve problems 13.To learn the three temperature scales, and how to convert between them. 14.To practice using problem solving techniques 15.To define density and its units

4. 3 The Language of Chemistry CHEMICAL ELEMENTS -CHEMICAL ELEMENTS - –pure substances that cannot be decomposed by ordinary means to other substances. Sodium Bromine Aluminum

5. 4 The Language of Chemistry The elements, their names, and symbols are given on the PERIODIC TABLEThe elements, their names, and symbols are given on the PERIODIC TABLE How many elements are there?How many elements are there? 117 elements have been identified 82 elements occur naturally on Earth 82 elements occur naturally on Earth Examples: gold, aluminum, lead, oxygen, carbon 35 elements have been created by scientists35 elements have been created by scientists Examples: technetium, americium, seaborgium

6. 5 The Periodic Table Dmitri Mendeleev (1834 - 1907)

7. 6 Chemistry - the science that deals with the materials of the universe, and the changes that these materials undergo. Branches of ChemistryBranches of Chemistry Organic chemistryOrganic chemistry Inorganic chemistryInorganic chemistry BiochemistryBiochemistry Physical chemistryPhysical chemistry An analytical chemistryAn analytical chemistry Each Branch offers: Many major areas of study for specializationMany major areas of study for specialization Several career opportunitiesSeveral career opportunities Also used in many other jobsAlso used in many other jobs

8. 7 1. Organic Chemistry Organic is the study of matter that contains carbonOrganic is the study of matter that contains carbon Organic chemists study the structure, function, synthesis, and identity of carbon compoundsOrganic chemists study the structure, function, synthesis, and identity of carbon compounds Useful in petroleum industry, pharmaceuticals, polymersUseful in petroleum industry, pharmaceuticals, polymers

9. 8 2. Inorganic Chemistry Inorganic is the study of matter that does NOT contain carbonInorganic is the study of matter that does NOT contain carbon Inorganic chemists study the structure, function, synthesis, and identity of non- carbon compoundsInorganic chemists study the structure, function, synthesis, and identity of non- carbon compounds Polymers, MetallurgyPolymers, Metallurgy

10. 9 3. Biochemistry Biochemistry is the study of chemistry in living thingsBiochemistry is the study of chemistry in living things Cross between biology and chemistryCross between biology and chemistry Pharmaceuticals and geneticsPharmaceuticals and genetics

11. 10 4. Physical Chemistry Physical chemistry is the physics of chemistry… the forces of matterPhysical chemistry is the physics of chemistry… the forces of matter Much of p-chem is computationalMuch of p-chem is computational Develop theoretical ideas for new compoundsDevelop theoretical ideas for new compounds HONK if you passed p-chem

12. 11 5. Analytical Chemistry Analytical chemistry is the study of high precision measurementAnalytical chemistry is the study of high precision measurement Find composition and identity of chemicalsFind composition and identity of chemicals Forensics, quality control, medical testsForensics, quality control, medical tests

13. 12 The Scientific Method A hypothesis is just a fancy name for a prediction. An observation is something that can be observed with the senses and recorded – it is very different from a theory. Theories do NOT become laws. A law tells what happens; it summarizes an observed behavior. A theory is our attempt to explain why it happened.

14. 13 Scientific Method 1.State the problem clearly. 2.Gather information. 3.Form a hypothesis. 4.Test the hypothesis. 5.Evaluate the data to form a conclusion. 6.If data supports hypothesis, continue testing until enough evidence is gathered to form a theory. (Theories can always be revised if needed after further testing.) If data does not support hypothesis, go back to step 3. 7.Share the results.

15. 14 Types of Observations and Measurements We make QUALITATIVE observations of reactions — changes in color and physical state.We make QUALITATIVE observations of reactions — changes in color and physical state. We also make QUANTITATIVE MEASUREMENTS, which involve numbers.We also make QUANTITATIVE MEASUREMENTS, which involve numbers. –Use SI units — based on the metric system (note: SI uses kg for mass instead of g)

16. 15 What is Scientific Notation? Scientific notation is a way of expressing really big numbers or really small numbers.Scientific notation is a way of expressing really big numbers or really small numbers. For very large and very small numbers, scientific notation is more concise.For very large and very small numbers, scientific notation is more concise. Scientific notation consists of 2 parts: A number between 1 and 10A number between 1 and 10 A power of 10A power of 10 N x 10 x

17. 16 To change standard form to scientific notation : Place the decimal point so that there is one non-zero digit to the left of the decimal point.Place the decimal point so that there is one non-zero digit to the left of the decimal point. Count the number of decimal places the decimal point has “moved” from the original number. This will be the exponent on the 10.Count the number of decimal places the decimal point has “moved” from the original number. This will be the exponent on the 10. If the original number was less than 1, then the exponent is negative. If the original number was greater than 10, then the exponent is positive.If the original number was less than 1, then the exponent is negative. If the original number was greater than 10, then the exponent is positive.

18. 17 Examples Given: 289,800,000Given: 289,800,000 Use: 2.898 (Decimal point moved 8 places. Decimal number was bigger than 10, so exponent is positive.)Use: 2.898 (Decimal point moved 8 places. Decimal number was bigger than 10, so exponent is positive.) Answer: 2.898 x 10 8Answer: 2.898 x 10 8 Given: 0.000567Given: 0.000567 Use: 5.67 (Decimal point moved 4 places. Decimal number was smaller than one, so exponent is negative)Use: 5.67 (Decimal point moved 4 places. Decimal number was smaller than one, so exponent is negative) Answer: 5.67 x 10 -4Answer: 5.67 x 10 -4

19. 18 To change scientific notation to standard form… Simply move the decimal point to the right (to create a decimal number bigger than 10) for a positive exponent of 10.Simply move the decimal point to the right (to create a decimal number bigger than 10) for a positive exponent of 10. Move the decimal point to the left (to create a decimal number smaller than 1) for a negative exponent of 10.Move the decimal point to the left (to create a decimal number smaller than 1) for a negative exponent of 10. (Use zeros to fill in places.)

20. 19Example Given: 5.093 x 10 6Given: 5.093 x 10 6 Answer: 5,093,000 (Exponent was positive, so decimal point moved 6 places to the right to get a decimal number greater than 10)Answer: 5,093,000 (Exponent was positive, so decimal point moved 6 places to the right to get a decimal number greater than 10) Given: 1.976 x 10 -4Given: 1.976 x 10 -4 Answer: 0.0001976 (Exponent was negative, so decimal point moved 4 places to the left to get a decimal number smaller than one)Answer: 0.0001976 (Exponent was negative, so decimal point moved 4 places to the left to get a decimal number smaller than one)

21. 20 Learning Check Express these numbers in Scientific Notation:Express these numbers in Scientific Notation: 1) 405789 2) 0.003872 3) 3000000000 4) 2 5) 0.478260

22. 21 Stating a Measurement In every measurement there is a  Number followed by a  Unit from a measuring device The number should also be as precise as the measurement!

23. 22 Standards of Measurement When we measure, we use a measuring tool to compare some dimension of an object to a standard. For example, at one time the standard for length was the king’s foot. What are some problems with this standard?

24. 23 SI measurement Le Système international d'unitésLe Système international d'unités The only countries that have not officially adopted SI are Liberia (in western Africa) and Myanmar (a.k.a. Burma, in SE Asia), but now these are reportedly using metric regularlyThe only countries that have not officially adopted SI are Liberia (in western Africa) and Myanmar (a.k.a. Burma, in SE Asia), but now these are reportedly using metric regularly Metrication is a process that does not happen all at once, but is rather a process that happens over time.Metrication is a process that does not happen all at once, but is rather a process that happens over time. Among countries with non- metric usage, the U.S. is the only country significantly holding out.Among countries with non- metric usage, the U.S. is the only country significantly holding out. Information from U.S. Metric Association

25. 24 Chemistry In Action On 9/23/99, $125,000,000 Mars Climate Orbiter entered Mars’ atmosphere 100 km lower than planned and was destroyed by heat. 1 lb = 1 N 1 lb = 4.45 N “This is going to be the cautionary tale that will be embedded into introduction to the metric system in elementary school, high school, and college science courses till the end of time.”

26. 25 UNITS OF MEASUREMENT Use SI units — based on the metric system LengthMassVolumeTimeTemperature Meter, m Kilogram, kg Seconds, s Celsius degrees, ˚C kelvins, K Liter, L

27. 26 Mass vs. Weight Mass: Amount of Matter (grams, measured with a BALANCE)Mass: Amount of Matter (grams, measured with a BALANCE) Weight: Force exerted by the mass, only present with gravity (pounds, measured with a SCALE)Weight: Force exerted by the mass, only present with gravity (pounds, measured with a SCALE) Can you hear me now?

28. 27 Metric Prefixes Kilo- means 1000 of that unitKilo- means 1000 of that unit –1 kilometer (km) = 1000 meters (m) Centi- means 1/100 of that unitCenti- means 1/100 of that unit –1 meter (m) = 100 centimeters (cm) –1 dollar = 100 cents Milli- means 1/1000 of that unitMilli- means 1/1000 of that unit –1 Liter (L) = 1000 milliliters (mL)

29. 28 Metric Prefixes

30. 29 Conversion Factors Fractions in which the numerator and denominator are EQUAL quantities expressed in different units Example: 1 in. = 2.54 cm Factors: 1 in. and 2.54 cm 2.54 cm 1 in.

31. 30 Learning Check Write conversion factors that relate each of the following pairs of units: 1. Liters and mL 2. Hours and minutes 3. Meters and kilometers

32. 31 How many minutes are in 2.5 hours ? Conversion factor 2.5 hr x 60 min = 150 min 1 1 hr 1 1 hr cancel By using dimensional analysis / factor-label method, the UNITS ensure that you have the conversion right side up, and the UNITS are calculated as well as the numbers!

33. 32

34. 33 Sample Problem You have $7.25 in your pocket in quarters. How many quarters do you have?You have $7.25 in your pocket in quarters. How many quarters do you have? 7.25 dollars 4 quarters 1 1 dollar 1 1 dollar X = 29 quarters

35. 34 You Try This One! If Jacob stands on Spencer’s shoulders, they are two and a half yards high. How many feet is that?

36. 35 Learning Check A rattlesnake is 2.44 m long. How long is the snake in cm? How long is the snake in feet?

37. 36 Learning Check How many seconds are in 1.4 days?

38. 37 Wait a minute! What is wrong with the following setup? 1.4 day x 1 day x 60 min x 60 sec 24 hr 1 hr 1 min 24 hr 1 hr 1 min

39. 38 English and Metric Conversions If you know ONE conversion for each type of measurement, you can convert anything!If you know ONE conversion for each type of measurement, you can convert anything! You must memorize and use these conversions:You must memorize and use these conversions: –Mass: 454 grams = 1 pound –Length: 2.54 cm = 1 inch –Volume: 0.946 L = 1 quart

40. 39 Learning Check Learning Check An adult human has 4.65 L of blood. How many gallons of blood is that? Equalities:1 quart = 0.946 L 1 gallon = 4 quarts Your Setup:

41. 40 Dealing with Two Units – Honors Only If your pace on a treadmill is 1.2 meters per second, how many minutes will it take for you to walk a distance of 8450 feet?

42. 41 What about Square and Cubic units? – Honors Only Use the conversion factors you already know, but when you square or cube the unit, don’t forget to cube the number also!Use the conversion factors you already know, but when you square or cube the unit, don’t forget to cube the number also! Best way: Square or cube the ENITRE conversion factorBest way: Square or cube the ENITRE conversion factor Example: Convert 4.3 cm 3 to mm 3Example: Convert 4.3 cm 3 to mm 3 4.3 cm 3 10 mm 3 1 cm 1 cm ( ) = 4.3 cm 3 10 3 mm 3 1 3 cm 3 1 3 cm 3 = 4300 mm 3

43. 42 Learning Check A Nalgene water bottle holds 1000 cm 3 of dihydrogen monoxide (DHMO). How many cubic decimeters is that?A Nalgene water bottle holds 1000 cm 3 of dihydrogen monoxide (DHMO). How many cubic decimeters is that?

44. 43 Solution 1000 cm 3 1 dm 3 10 cm 10 cm ( ) = 1 dm 3 So, a dm 3 is the same as a Liter ! A cm 3 is the same as a milliliter.

45. 44 Buying Mulch How many cubic yards of mulch will you need to cover a 20 ft by 30 ft play area to a depth of 6 inches? (Find volume of mulch in feet cubed, then convert to yards cubed.)

46. 45 Three targets with three arrows each to shoot. Accuracy and Precision Both accurate and precise Precise but not accurate Neither accurate nor precise How do they compare? Accuracy - Accuracy is how close a measured value is to the actual (true) value. Precision - Precision is how close the measured values are to each other (how repeatable the results are). Precision is influenced by how small of a measuring increment is used, and is shown by how many significant digits are in the recorded answer.

47. 46 Significant Figures The numbers reported in a measurement are limited by the measuring tool The numbers reported in a measurement are limited by the measuring tool Significant figures in a measurement include the known digits plus one estimated digit Significant figures in a measurement include the known digits plus one estimated digit

48. 47 Equalities State the same measurement in two different units length 10.0 in. 25.4 cm

49. 48 Always estimate ONE place past the smallest mark! Significant figures:

50. 49 Counting Significant Figures RULE 1. All non-zero digits in a measured number are significant. Number of Significant Figures 38.15 cm 4 5.6 ft 2 65.6 lb 122.55 m

51. 50 Leading Zeros RULE 2. Leading zeros in decimal numbers are NOT significant. They just serve as placeholders (indicate the position of the decimal point). Number of Significant Figures 0.008 mm1 0.0156 oz3 0.0042 lb 0.0042 lb 0.000262 mL

52. 51 Sandwiched (Captive) Zeros RULE 3. Zeros between nonzero numbers are ALWAYS significant. Number of Significant Figures 50.8 mm3 2001 min4 0.702 lb 0.00405 m

53. 52 Trailing Zeros RULE 4. Trailing zeros in numbers without decimals are NOT significant. They are only serving as place holders. Number of Significant Figures 25,000 in. 2 25,000 in. 2 200. yr3 200. yr3 48,600 gal 48,600 gal 25,005,000 g

54. 53 Counted numbers and definitions Rule 5. ACTUALLY COUNTED numbers are EXACT, so they have an INFINITE number of significant digits. Definitions (which includes conversions between metric units) have an infinite number of significant digits.

55. 54 Learning Check A. Which answers contain 3 significant figures? 1) 0.4760 2) 0.00476 3) 4760 B. All the zeros are significant in 1) 0.00307 2) 25.300 3) 2.050 x 10 3 C. 534,675 rounded to 3 significant figures is 1) 535 2) 535,000 3) 5.35 x 10 5 1) 535 2) 535,000 3) 5.35 x 10 5

56. 55 State the number of significant figures in each of the following: A. 0.030 m B. 4.050 L C. 0.0008 g D. 3.00 m E. 364 cars Learning Check

57. 56 Significant Numbers in Calculations A calculated answer cannot be more precise than the measuring tool. A calculated answer cannot be more precise than the measuring tool. A calculated answer must match the least precise measurement. A calculated answer must match the least precise measurement. Significant figures are needed for final answers from Significant figures are needed for final answers from 1) multiplying or dividing 1) multiplying or dividing 2) adding or subtracting

58. 57 Multiplying and Dividing Round (or add zeros) to the calculated answer until you have the same number of significant figures as the measurement with the FEWEST significant figures.

59. 58 Learning Check A. 2.19 X 4.2 = 1) 9 2) 9.2 3) 9.198 B. 4.311 ÷ 0.07 = 1) 61.58 2) 62 3) 60 C. 2.54 X 0.0028 = 0.0105 X 0.060 1) 11.32) 11 3) 0.041

60. 59 Adding and Subtracting The answer has the same number of decimal places as the measurement with the fewest decimal places. 25.2 one decimal place + 1.34 two decimal places 26.54 26.54 answer 26.5 one decimal place

61. 60 Learning Check In each calculation, round the answer to the correct number of significant figures. A. 235.05 + 19.6 + 2.1 = 1) 256.75 2) 256.83) 257 B. 58.925 - 18.2= 1) 40.725 2) 40.733) 40.7

62. 61 Temperature Scales FahrenheitFahrenheit CelsiusCelsius KelvinKelvin Anders Celsius 1701-1744 Lord Kelvin (William Thomson) 1824-1907

63. 62 Calculations Using Temperature Generally require temp’s in kelvinsGenerally require temp’s in kelvins T (K) = t (˚C) + 273.15T (K) = t (˚C) + 273.15 Body temp = 37 ˚C + 273 = 310 KBody temp = 37 ˚C + 273 = 310 K Liquid nitrogen = -196 ˚C + 273 = 77 KLiquid nitrogen = -196 ˚C + 273 = 77 K Generally require temp’s in kelvinsGenerally require temp’s in kelvins T (K) = t (˚C) + 273.15T (K) = t (˚C) + 273.15 Body temp = 37 ˚C + 273 = 310 KBody temp = 37 ˚C + 273 = 310 K Liquid nitrogen = -196 ˚C + 273 = 77 KLiquid nitrogen = -196 ˚C + 273 = 77 K

64. 63 Temperature Scales 1 kelvin = 1 degree Celsius Notice that 1 kelvin = 1 degree Celsius Boiling point of water Freezing point of water Celsius 100 ˚C 0 ˚C 100˚C Kelvin 373 K 273 K 100 K Fahrenheit 32 ˚F 212 ˚F 180˚F

65. 64 Fahrenheit Formula – Honors Only Freezing point of water: 0°C = 32°F Bioling point of water: 100°C = 212°F Bioling point of water: 100°C = 212°F °F = 9/5 °C + 32 °C = 5/9 (°F - 32) °C = 5/9 (°F - 32) Convert 37 °C to °F Convert –40 °F to °C

66. 65 DENSITY - an important and useful physical property Mercury 13.6 g/cm 3 21.5 g/cm 3 Aluminum 2.7 g/cm 3 Platinum

67. 66 DENSITYDENSITY Density is an INTENSIVE property of matter.Density is an INTENSIVE property of matter. –does NOT depend on quantity of matter. –temperature Contrast with EXTENSIVEContrast with EXTENSIVE –depends on quantity of matter. –mass and volume. Styrofoam Brick

68. 67 Problem A piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm 3 ).

69. 68 Strategy 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3.Calculate the density. 4. Round for correct number of significant digits.

70. 69 Learning Check Osmium is a very dense metal. What is its density in g/cm 3 if 50.00 g of the metal occupies a volume of 2.22cm 3 ?

71. 70 Learning Check If blood has a density of 1.05 g/mL, how many liters of blood are donated if 575 g of blood are given?

72. 71 Learning Check What is the density (g/cm 3 ) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL? vol. of water: vol. of metal: 25 mL 33 mL Density of metal:

73. 72 Learning Check Which diagram represents the liquid layers in the cylinder? (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) 2) 3) K K W W W V V V K